1. Field of the Invention
This invention relates to tensioning devices in general, and more particularly to a tensioning device or autotensioner for a tensioned belt, chain or the like.
2. Description of the Prior Art
For a belt tensioner, in an automobile belt transmission device there has been developed a hydraulic tensioner or autotensioner of the force-feed type. The hydraulic tensioner of the force-feed type must be arranged in an oil pan or reservoir due to the leakage of oil out of the tensioner. Especially when an automobile timing belt is arranged outside the oil pan, it is impossible to use a hydraulic tensioner of the force-feed type because of such oil leakage.
On the other hand, a hydraulic autotensioner of the sealed type has been well known. In such a known tensioner, a plunger stroke in the large diameter side of the hydraulic tensioner does not result in a long piston stroke in the smaller diameter side of the tensioner.
To provide a solution to these problems, there is herein described a hydraulically operated tensioner for varying a stroke of the piston in accordance with a stroke of the plunger. By the use of such a hydraulic tensioner, the stroke of the piston can become long.